1. Field of the Invention
The present invention relates to a network relay device and a ring network. In particular, it relates to a network relay device with a forwarding database (FDB) and a ring network.
2. Description of the Related Art
Conventionally, a switch is known that has a packet kind determining unit for determining a frame kind from header information extracted from a received frame, and extracting a destination MAC address from the header information, a database for associating the destination MAC address with an output port, a packet destination determining unit for determining the output port from the database using the destination MAC address extracted by the packet kind determining unit, a packet forwarding unit for extracting the header information from the received frame and transmitting it to the packet kind determining unit, and for receiving the output port from the packet destination determining unit and transmitting the frame from that output port, and a generating unit for generating a receiver searching message, in which when detecting failure in a downstream network, an entry in the database is flushed to transmit the receiver searching message to the downstream network.
The above configured switch can, even in case of failure in a ring network, restore undesired traffic for a short period of time, and minimize deterioration in security.
Refer to JP-A-2007-324688, for example.
However, applying a ring network with that switch disclosed by JP-A-2007-324688 to, for example, a large capacity communication network backbone (broadband network) connecting telecommunications carriers, leads to large amounts of data transmitted through the backbone, and therefore large amounts of information registered in an FDB of that switch. This requires a long period of time of erasing the information registered in the FDB according to FDB flush frames, and may therefore affect the period of time of route switching in case of failure in the ring network.